A3976KLB データシートの表示（PDF） - Allegro MicroSystems
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A3976KLB Datasheet PDF : 5 Pages
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Page 5 of 5
3976 Dual Protected PWM Motor Driver
APPLICATION NOTES
Open Lead Protection. During normal PWM
operation diagnostic circuitry will look for a minimum
source current level after a bridge is signalled on.
Additionally, the diode flyback is monitored on the proper
output. The logic will signal a fault and disable the outputs if
it determines that the current is below the minimum level
AND no flyback is occurring. If the inductive load is too
large, the current would take too long to reach the minimal
level and a false open load would be reported. It is
recommended that the inductive load be less than 38mH.
Short Circuit Protection. Internal sense resistors in
series with VBB and ground will trip the fault circuitry if
greater than 1.1A is detected. To prevent false overcurrent
events due to reverse recovery spikes of the clamp diodes,
the current monitor is blanked for 5us after a high side is
signalled to turn on. If an additional input command follows
after the initial fault, the selected pair of drivers will pulse on
for the 5us blanking duration. The short circuit fault will
remember the input state where the fault occurred and will
wait for that particular logic state after the short has been
removed before normal operation is allowed to resume.
Thermal Protection. Circuitry turns OFF all drivers
when the junction temperature reaches 170°C typically. It is
intended only to protect the device from failures due to
excessive junction temperatures and has a hysteresis of
approximately 15°C.
Layout. The printed wiring board should use a heavy
ground plane. For optimum electrical and thermal
performance, the driver should be soldered directly onto the
board. The load supply pin, VBB, should be decoupled with
an electrolytic capacitor (> 47 µF is recommended) placed as
close to the device as possible.
Terminal List
Pin Name
VBB
ENABLE1
PHASE1
GROUND
OUT1A
FAULT1
OUT1B
OUT2B
FAULT2
OUT2A
PHASE2
ENABLE2
VCC
NC
Pin Description
Motor Supply Voltage
Control Logic – Bridge 1
Control Logic – Bridge 1
Power Ground Return
Bridge 1 Output
Diagnostic Output
Bridge 1 Output
Bridge 2 Output
Diagnostic Output
Bridge 2 Output
Control Logic – Bridge 2
Control Logic – Bridge 2
Logic Supply
No Connect
24 Lead SOIC
1
2
3
18,19,6,7
9
11
12
13
14
16
22
23
24
3,4,5,8,15,17,20,21
16 Lead DIP
1
2
3
4,5,12,13
6
7
8
9
10
11
14
15
16
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